Davy7/26/2026, 2:45:27 AM

Dragging the 4-stem accompaniment master recomputed `ratio = newValue /
max(drums, bass, other)` from the last rendered store snapshot on every slider
event, then dispatched each sub-stem through its own 20ms trailing limiter into
an independent async round-trip. During a fast drag the three stems were scaled
by factors sampled at different, partially-committed moments, so they drifted
apart; whichever stem saturated at 1 captured the max-derived master and pinned
it, and the lossy `Math.min(1, …)` clamp destroyed the mix ratios for good.

Freeze a per-gesture base at pointerdown and map every sub-stem as a pure
function of the master value from that base, so the mapping is idempotent and
reversible through the clamp. Commit the three stems through a single trailing
limiter so a throttled flush always carries a consistent triple, and flush on
release. While dragging, render the master thumb from the gesture value instead
of max(sub-stems) so a saturated stem cannot pin it.

Also release the gesture explicitly when the slider disappears without a
pointerup (song ends, mixer popup closes) or the track changes mid-drag —
otherwise the next drag would scale the new mix by the previous song's ratios —
and hold the released value until the store reflects it, so the thumb does not
hop backwards for one IPC round-trip. Unmuting now restores each sub-stem's own
level instead of collapsing all three to one value.

Co-authored-by: Claude Fable 5 <noreply@anthropic.com>

Parent40f2d5b